Conventionally, there has been proposed a drive recorder which mounts a camera capable of photographing a moving image on a vehicle and records a picture at an accident. Image data in the drive recorder is digital data and has a feature of being easily edited with a computer. Therefore, there is also a possibility that fraudulence is committed cleverly by unit which modifies a picture of an accident by editing image data to be used for evidence. Hence, a drive recorder is disclosed in a patent Document 1, which encodes and records data to enhance credibility of image data as evidence.
While credibility of image data as evidence is enhanced according to the patent Document 1, no one but a specific person (public organization, insurance company, or the like), who has a decoding key can decode the image data, and therefore it becomes difficult for a driver personally to confirm contents of the image data. Also, back up image data is desired for maintaining image data more securely at an accident occurrence, but the patent Document 1 does not have such a consideration and there is a room to be improved.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-352128